December 21, 2005

Play Break!

by hilzoy

Time for a break from the NSA story. While doing actual work, I ran across a fascinating study (behind subscription wall) in Evolution and Human Behavior. It's called 'Sex differences in response to children’s toys in nonhuman primates (Cercopithecus aethiops sabaeus)'.

Here's what it's about: as most parents know, little boys tend to be more interested in toys like trucks, and little girls in toys like dolls. (I was an exception: someone gave me a doll once, and I dissected it.) There is no obvious way to decide whether this is innate or a cultural artifact by watching human children. So why not see whether the same gendered toy preferences exist in, oh, vervet monkeys?

Guess what? They do.

"The percent of contact time with toys typically preferred by boys (a car and a ball) was greater in male vervets (n = 33) than in female vervets (n = 30) ( P < .05), whereas the percent of contact time with toys typically preferred by girls (a doll and a pot) was greater in female vervets than in male vervets ( P < .01). In contrast, contact time with toys preferred equally by boys and girls (a picture book and a stuffed dog) was comparable in male and female vervets. The results suggest that sexually differentiated object preferences arose early in human evolution, prior to the emergence of a distinct hominid lineage."

Discuss.

(Graphs and photos below the fold.)

Description, from the article: "Fig. 1. Percent contact (means±S.E.M.) with "masculine," "feminine" and "neutral" toys for male and female vervets. Percent contact with "masculine" toys is greater in male than in female animals (P

From the article: "Fig. 2. Examples of a female and a male animal contacting toys. The female animal (left) appears to be conducting an anogenital inspection of the toy doll, similar to inspections of infant vervet monkeys. The male animal (right) appears to be moving the car along the ground in a manner similar to that a child might use."

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In "Play Break," Hilzoy writes: Here's what it's about: as most parents know, little boys tend to be more interested in toys like trucks, and little girls in toys like dolls. (I was an exception: someone gave me a... [Read More]

Tracked on December 22, 2005 at 02:06 PM

Comments

Ah, but did they control for vervet culture, i.e., were these scores compared against a human or other primate control group?

Now just a minute. I'm a boy and I loved my Fisher-Price Adventure people. And they're, you know, doll-like.

Of course, my friends and I used to divide the front yard into different countries, each with different forms of government (The Poo King, etc), currencies (yellow-coloured rocks v. silver coloured rocks) and legal systems (which tended towards the arbitrary). I don't know what the means to gender preferences. But politics is universal.

I find it moderately incredible, on first principles, that vervet gender differentiation encompasses identifing pots as feminine. I mean, neither male or female vervets does anything resembling cooking; how could a female preference for pots have come about? Even if there were some general primate gender differentiation that in humans expresses itself as a feminine attraction toward tools used in cooking (like, say, a general feminine tendency to provide food to others), wouldn't a vervet have to comprehend cooking on a level that would require a lot of education/training (which might screw up the study itself) before the vervet version of that gender differentiation attached itself to a toy pot?

(On a cross cultural note, in the one non-Western culture I am intimately familiar with, Samoa, cooking is a men's task. Samoan kids I knew didn't have a lot of toys, but I'd like to see this experiment run on kids in Samoa.)

I can conceive of a gendered difference in preference for toys representing infant care, like dolls. I can conceive of a gendered difference in preference for toys suited to throwing or bouncing or rolling, like trucks or balls. The idea that a monkey could have a gendered preference for playing with a pot, given that cooking forms no part of its evolutionary history, seems so ludicrous to me that I worry about the status of the rest of the study.

Ok, a bit more serious for a second. A red pan? What is the argument, exactly, for why there would be dimorphism surrounding red pans, orange balls, etc.? I understand that there are hormonal effects (amond other things) that lead females to have specific responses to "babies" (and the doll here has typical baby proportions), but (depending on the structure of the study) it is possible that the female bias towards the "doll" does some of the work in explaining the other data. Since these are "percent time" of contact I'm assuming that the vervet's were given choices between a range of toy combinations....

Also, we've got a picture of the doll -- hilzoy, is there a picture of the dog you could put up? Because from a human gender stereotyping point of view, the difference between a doll and a toy dog is that one is a pretend infant of one's own species, and the other isn't. I'd like to look at the dog (presumably furry and fourlimbed) before evaluating the study on the basis that the vervets reacted to a non-furry, (clothed? hard to tell) doll as a representation of a baby vervet, and reacted to the dog as not a representation of a baby vervet. (Or I'd like to know what the researchers thought on the subject.)

LB: Yes; likewise, trucks. "The six toys were selected because children in a broad age range categorize them as "masculine," "feminine," or "neutral" and, for those toys categorized as "masculine" or "feminine," the sex difference in toy preferences is reliable and relatively large in children." I don't think they were going for plausibly culture-neutral toys; just toys that human children seem to reliably identify one way or the other. They were just interested in seeing whether, and to what extent, human children's performance was repeated in vervets.

I don't think they had any sort of hypothesis about why vervets, or human children for that matter, identify pots as feminine toys. About the closest they come is this part of the discussion section:

"Information is not yet adequate to know what low-level perceptual properties may contribute to the responses to sex-typed toys by vervet monkeys and this study was not designed to evaluate these hypothetical feature preferences. However, toys preferred by girls have been described as objects that afford opportunities for nurturance (Campbell; Eisenberg and Miller), and selection pressures may favor responsiveness to object cues (e.g., an animate-like form) that signal maternal behavior because these cues enhance infant survival. A doll, for example, may be of greater interest to females than males in primate species where females interact with infants more than males do. Such species include humans (Blakemore, 1981) and vervet monkeys (Lancaster and Meaney). However, as we found no sex differences in response to toy categories based on an animate-like (doll, dog) or inanimate-like (car, ball, book, pan) distinction, it appears that other characteristics contributed to the female object preferences we observed.

Color may also provide an important cue for female interest. Female rhesus monkeys have been found to show a preference for the characteristic "reddish-pink" facial coloration of infant vervets compared to yellow or green. Consistent with this female color preference, girls are also more likely than boys to prefer warmer colors (i.e., pink and red) to cooler colors (i.e., blue and green) (Minamoto, 1985 cited in Iijima, Arisaka, Minamoto, & Arai, 2001). A preference for red or reddish pink has been proposed to elicit female behaviors to infants that enhance infant survival, such as contact (Higley, Hopkins, Hirsch, Marra, & Suomi, 1987). The hypothesis that reddish pink or red may be a cue signaling opportunities for nurturance and thus eliciting female responsiveness could explain our finding of greater female contact with both the doll (with a pink face) and the pot (colored red).

Toys preferred by boys, such as the ball and police car used in this research, have been characterized as objects with an ability to be used actively (O'Brien & Huston, 1985) or objects that can be propelled in space (Benenson, Liroff, Pascal, & Cioppa, 1997). Preferences for such objects may exist because they afford greater opportunities for engaging in rough or active play. In humans, these characteristics have in turn been suggested to relate to targeting or navigating abilities (for discussion, see Alexander, in press) that might be particularly useful for males for purposes of hunting or locating food or mates (Eals; McBurney and Silverman). As suggested for females in regard to objects that signal nurturance, males may therefore have evolved preferences for objects that invite movement."

LB: the preceding 'yes; likewise trucks', expanded, reads: yes, pots are only culturally female; likewise, trucks are -- well, not 'culturally male', but a lot of their meaning to little boys might come from knowing e.g. that people drive them, which would, I assume, be lost on little boy vervet monkeys.

No pictures of the dog, alas. The two pictures I posted are all there were.

Okay. I'm now in full knee-jerk mode, but when a study of monkeys shows that they have the same gender preferences as modern-day American children (girls cook and prefer pink, boys drive trucks and prefer blue) rather than, say, Samoan children, where the boys cook and the girls don't, or nineteenth century British children, where blue was regarded as a feminine color for children and pink was masculine, I have to say that I want a lot of replication on a lot of different monkeys by a lot of different researchers before I take it seriously.

LB: I love seeing studies replicated, and I tend to take them as data points, pure and simple, whose explanations remain to be determined.

That said, I find the idea that females of any species in which females care for infants (e.g., not sea-horses or fish) would be disproportionately attracted to the color of their infants' faces plausible.

The truck didn't bother me too much -- I can conceive of a non-cultural category you could put a toy truck in: the rolling quality of it makes it a toy that can easily be projected through space, and it seems possible that that could relate to a real gender difference.

What I really want to do is to test the researchers -- make them rerun the experiment with, say, Malibu Barbie's Corvette rather than a police car, or generally toys that are heavily gender-loaded in an indubitably cultural rather than innate way, and see if the vervets still prefer the toys that an American child of their gender would.

Preferences for such objects may exist because they afford greater opportunities for engaging in rough or active play. In humans, these characteristics have in turn been suggested to relate to targeting or navigating abilities (for discussion, see Alexander, in press) that might be particularly useful for males for purposes of hunting or locating food or mates (Eals; McBurney and Silverman). As suggested for females in regard to objects that signal nurturance, males may therefore have evolved preferences for objects that invite movement."

This is weird, as a cross-species statement about primates. Do male vervets, or male primates generally, provide any significant food to females such that locating food would be a behavior characteristic more of males than of females? My understanding is that this is not true -- that for most species of primate each individual, for the most part, feeds itself.

I'm nitpicking here, but I think reasonably so -- someone who identifies 'locating food' as related to innate gender differentiation in primates generally seems to be thinking about gender differentiation in an oddly unexamined way.

It's telling that the sex difference in behavior for the red pan was less (percentagewise) than for the other three differentiated toys (truck, ball, doll). I would only really worry about the study if the pan difference were greater.

There are a bunch of possible explanations, but here's mine: the male vervets may have found the pot appealing but became frustrated when it failed to move in the same useful, predictable way as the truck or ball.

I was thinking about my own toy preferences. I didn't care for soldiers and such. What I loved were machines. -- I said I dissected the doll; that was for effect. What really happened was: it was one of those Baby Secret dolls that had a string in back; when you pulled it it would say something like "Oooh, Mommy, I love you!" I thought that this was nauseating, but that it would be really cool to figure out how it worked, and whether I could get it to say something more interesting. So I took Baby secret apart.

I also loved monsters, and anything that would have felt at home in a museum of natural history. (I had a series of museums in the basement, all modeled on the museum of natural history at Harvard, which I adored. The bug museum; the rock museum; the dioramas of villages of distant peoples museum; etc.)

Once upon a time, I was driving, and as I sometimes do when I'm driving or otherwise bored, I started thinking about a random question, in this case: what would the history of Western art have been like had Christ's gender not been known? This somehow led to: how would it be possible to do a female crucifixion now, given that all the obvious ways would just look like a bad cover for Hustler? Yu'd have to do something that acknowledged and co-opted the commercialization of images of female pain and torture, I thought. And this, somehow, led to the thought: Obviously! A crucified Barbie doll!

And since I am the sort of person who actually does stuff like this, I made one. At one point, an entire diorama sort of thing, which was quite odd. I eventually tossed the diorama thing. But I kept the crucified Barbie, since one never knows when one might need one.

Then (a few years later, I was living in faculty housing at my first job, and an architect employed by the college I worked at needed to get in to do some measurements, accompanied by this really neurotic dean who I had never much liked, and who had absolutely no imagination or sense of humor or anything. The architect was poking around one of my closets, and suddenly popped out and said: why is there a crucified Barbie doll in here?

And the neurotic dean got all strange about it -- this during the period when political correctness was at its height -- and wanter to know exactly why I had a crucified Barbie doll in my closet. I explained, and she looked at me with a look of great distaste, and said:

Do you often make art involving the torture and mutilation of women?

Oh dear, I thought. One of those moments when you know that you're already lost, whatever your original feminist impulse in making a crucified Barbie, and however long you spent working in battered women's shelters.

I conducted endless "science" experiments in our basement. Some with a chemistry set, naturally utterly ignoring any and all instructions.

Taking apart transformers and blowing out the house's power system was a specialty.

My own Natural History Museum -- that is, my model, not the insect studies I conducted in back and front yards, or the frog-egg-hunting expeditions I mounted in the woods in CT -- was the American, in Manhattan. That, and the Brooklyn Museum, were the constant museums of my childhood.

And when I say "constant," in the case of the Brooklyn Museum -- whose African art collections, and Egyptian collections, among others, are world-class, even if the Egyptian is only the second best in NYC -- since it was just down the street on Eastern Parkway from the Main Branch of the Brooklyn Public Library at Grand Army Plaza, is that for many years I would be there, dividing time between each, two out of three weekends, and on plenty of additional weekdays, as well. I ended up doing all sorts of unpaid jobs for the BM, from junior docent, to supervising the young kids doing workshops, and so on, over the years until I was 13 or so. (Requiring me for long periods of time to be at the BM 4 weekends out of 4, and some weekday evenings each week.)

(I've not been back to the Brooklyn Museum since before the remodeling.)

The Am. Museum of Natural History in Manhattan, though, also much time. Then the Metropolitan. Then some of the others. (NYC literally has hundreds of museums, and I'm using "literally" correctly, which seems rarer and rarer these days; guess how I feel about that?)

Lytton Strachey, from his extremely catty bio of Florence Nightingale:

"Ah! To do her duty in that state of life unto which it had pleased God to call her! Assuredly she would not be behindhand in doing her duty; but unto what state of life had it pleased God to call her? That was the question. God’s calls are many, and they are strange. Unto what state of life had it pleased Him to call Charlotte Corday, or Elizabeth of Hungary? What was that secret voice in her ear, if it was not a call? Why had she felt, from her earliest years, those mysterious promptings towards … she hardly knew what but certainly towards something very different from anything around her? Why, as a child in the nursery, when her sister had shown a healthy pleasure in tearing her dolls to pieces, had she shown an almost morbid one in sewing them up again?"

Previous research from the US into Barbie abuse suggested that prepubescent girls destroyed the doll because she reminded them of adulthood at a time when they were still clinging to their childhood, but Dr Nairn found no evidence of this.link

The article has a bit more detail. Perhaps I am revealing a sadistic streak in me, but the idea of naming my research area 'Barbie abuse' has a faint appeal, especially because the Japanese Ministry of Education tracks faculty research interests.

So it turns out that if you google "whales" and "fear," Google will show this thread as #1. And it's #4 for "fear of whales."

Which is why not closing off comments on a post after some fixed period, be it 3 weeks or not, is a bad idea. (Of course there's a way to do it; I can't advise you, but someone who understands your template and publishing system should be able to.) Even if whichver system it is (MT? Another?) doesn't provide it as an option with a button, it's fixable in the code. Surely someone around here must be able to help?

Anyway, just a suggestion, of course. Maybe you guys don't mind that sort of thing.

When Barbie returns, and it will be soon (though it would be more convincing if the crucified Barbie had been mysteriously missing from Hilzoy's closet/cave/crypt), those who have prevented Her dissection in science classrooms across the country will be eternally punished.

Hmm... two-way tests show that while females prefer the doll, the male relationship isn't strong at all:
within-sex comparison of contact scores showed that female vervets had greater percent contact with "feminine" over "masculine toys," P<.01, but males had similar percent contact with "masculine" and "feminine" toys, P=.19.
...
However, although female vervets preferred "feminine" toys over "masculine" toys, male vervets did not appear to prefer "masculine" toys over "feminine" toys. This difference between male vervets and boys may indicate that toy preferences in boys are directed by gender socialization to a larger degree than are toy preferences in girls.

That's not nearly as shocking a conclusion, but much more believable from an evo-psych perspective.

I hate to be too Freudianly obvious, but shouldn't someone note that the female preference for pots might have to do not with their role in cooking - which others have noted would not be apparent to most non-humans - but as concave objects?

I missed the monkey porn story. It goes both ways, I guess. I recall, many years ago, going to a zoo with a then-girlfried, and a mangabey becoming very interested in her. Well, there wasn't anyone else around, and we did experiment a little with different positioning -- nothing you coundn't see on TV nowadays. The monkeys seemed to enjoy her, and seemed to wish me nothing but ill.

Btw: I'm away until early on the evening of the 25th, with sporadic internet access at best.

I hope everyone has a wonderful Christmas, a Happy Hanukkah, a delightful Eid al-Fitr, a marvelous Kwanzaa, a superb solstice, and every other pleasant holiday imaginable. (I've always thought that people should be happy all the time; why should holidays be especially controversial?)

Yeah, an odiferous orielly to everyone and, of course Merry Christmas and Happy New Year and whatever you need to make the next year a better one than last ..

... so my opening page is MSN, and there is a headline touting Osama Bin Laden's niece and her centerfold photo montage in GQ magazine, which just about now is causing both Osama's and Paul Cella's heads to explode simultaneously, in some sort of cross-cultural, border-incursion, orthagonal kind of way. Large brain splatter in caves everywhere.

The President of Iran bans western music. The Republican Party should be so lucky to have that power. You know, except for the Republicans here, who seem to be cool, which puts a crimp in the generalizations.

The President of Iran bans western music. The Republican Party should be so lucky to have that power. You know, except for the Republicans here, who seem to be cool, which puts a crimp in the generalizations.

Listening to Butthole Surfers' "Hairway to Steven" while snapping green beans for tomorrow's dinner. I guess I'll beat them into submission with the crock pot because I dont have a pressure cooker.

(I've always thought that people should be happy all the time; why should holidays be especially controversial?)

Bad little boys and girls used to get lumps of coal, now it's RFID chips so grumpy old men can monitor if the kids are playing in their yard. Why the hell are all the truant officers on holiday this time of year?

Good comment DaveC.
The truant officers or police officers can't keep up with all the vandalism and crime that is taking place this day and time.
A person must be on guard at all times.
Did you know Christmas is one of the most stressful times of the year for most people?
Maybe someone will buy you a pressure cooker for Christmas. I hear they can be dangerous so be careful should you receive one.
Enjoy those green beans.
Merry Christmas.

In the mall they were offering neck rubs to try and sign you up for a health club or some other cult-like thing. It creeped me out, plus there are all of those people that are milling around. From now on I'm only shopping at Farm and Fleet. or Fleet Farm. Home Depot makes me nervous because something could fall on you.
Merry Christmas

I'm waiting up for my son to return from the Festivus party, whatever that is.

What a bunch of Grinches you guys are! Well it is true that this season can be stressful. Last year one of my students was so stressed that she threw up off the porch of my portable. So I won't wish any one a merry holiday, just a good survival rate and maybe some fun afterwards. Cheers, regardless.

Eid al-Fitr was back around November 3. It's been several years since it happened to be near Christmas. The Muslims don't resync their lunar calendar like the Jews do, so their holidays rotate through the seasons.

Lily, I certainly don't feel like a grinch!
As a matter of fact this is has been the happiest Christmas season I have had in Years.
I'm glad I did my shopping throughtout the year so I have more time for family.

Setting aside all the negetivety that is taking place in the world and
saying a praying for the men and women in Iraq.

So many people seem to forget what the season is really about. The birth of Christ.
And God Bless Us All.
Off I go for another beatutiful fortunate day!